FORMATION CONSTANTS AT HIGH IONIC STRENGTH--I. POTENTIOMETRIC DETERMINATION OF PROTONATION CONSTANTS FOR SUCCINIC, PROPIONIC AND MONO-METHYL SUCCINIC ACID IN DIFFERENT IONIC MEDIA

摘要

The protonation constants, K_r for the ligands succinic acid (SA), mono-methyl succinate (MS) and propionate (PA) have been determined, at 25°C, by glass electrode potentiometry in 3 mol/dm~3 (M) NaNO_3. KNO_3, NH_4NO_3, Ca(NO_3)_2 and Et_4NBr aqueous media. Results are compared with literature constants determined in 3 M NaClO4. The order of stability was found to be K_1(SA) > K_1(PA) > K_1(MS)> K_2,(SA) and for the ligands in the different media K_r followed the general trend with respect to the background electrolyte Et_4NBr > NaClO_4 > KNO, > NaNO_3 > NH_4NO_3 > Ca(NO_3)_2.